Valve operator with explosive cartridge

ABSTRACT

A valve operator incorporates an explosive actuator which includes an elongated twisted steel tube, for emergency use in, for example, closing a valve quickly. When the emergency arises, the explosive charge in the twist actuator is fired and the gases generated by the explosion cause the twisted steel tube to untwist. One end of the twist actuator is fixed. The other end, which is free to rotate, is connected to the valve stem. Rotation of the free end of the twist actuator moves the valve quickly to the desired emergency position, which may be either the closed or open position. Two forms are disclosed. In one, the twisted-tube actuator is a series component of the normal gear drive. In the other, the actuator is coupled or decoupled by a clutch mechanism.

baited States Patent [1 1 Ball, Jr. et al.

[ Oct. 23, 1973 VALVE OPERATOR WITH EXPLOSIVE CARTRIDGE [75] Inventors: Russell C. Ball, Jr.; Walter J.

Denkowski, both of Malvern, Pa.

[73] Assignee: Philadelphia Gear Corporation,

King of Prussia, Pa.

22 Filed: Apr. 24, 1972 T U [21] Appl. No.: 246,990

52 U.S. Cl 74/625, 137/68, 123/24 A, 60/23, 89/1 B [51] Int. Cl. F16h 35/00 [58] Field of Search 123/24 A; 60/23; 137/68; 74/625; 89/1 R [56] References Cited UNITED STATES PATENTS 2,704,947 3/1955 Hopkins 74/625 2,980,085 4/1961 Schneider.... 123/24 A 2,885,906 5/1969 Cupedo 74/625 3,022,793 2/1962 Thorp, Jr. 137/68 Primary Examiner-Manuel A. Antonakas Assistant ExaminerWesley S. Ratliff, .lr. Att0rneyHenry N. Paul, Jr. et a1.

[57] ABSTRACT A valve operator incorporates an explosivev actuator M which includes an elongated twisted steel tube, for

position, which may be either the closed or open position. Two forms are disclosed. In one, the twisted-tube actuator is a series component of the normal gear drive. In the other, the actuator is coupled or decou pled by a clutch mechanism.

12 Claims, 9 Drawing Figures EXPLOSIVE CHARGE PATENIED EDT 23 I873 SHEET 10F 5 CHARGE EXPLOSIVE PATENTEDUBT 23 I975 SHEET 3 OF 5 7 EXPLOSIVE CHAR VALVE OPERATOR WITH EXPLOSIVE CARTRIDGE BACKGROUND OF THE INVENTION Pipe-line valves are sometimes located in locations which are not served by power distribution lines. Or, there may be a power failure in the power distribution line. In either case, a service man may need a considerable amount of time to reach the valve, and, having reached the valve, it may take the service man a further considerable amount of time to close the valve manually. Yet emergency situations may develop which may make it necessary to close (or open) the valve quickly.

SUMMARY OF THE INVEN TION An object of the present invention is to provide a valve operator device adapted, in an emergency situation, to put a valve very quickly in a desired condition, which may be either the closed or open position.

A further object is to provide a valve operator having the capabilities just mentioned which may be triggered from a remote location without use of power distribution lines.

The foregoing objects are achieved, in accordance with the present invention, by providing a valve operator which incorporates an explosive cartridge twisttube actuator. One end of the twist-tube actuator is fixed against rotational movement. The other end is free to rotate through an angle within a range such, for example, as 60 to 120. When the cartridge is exploded (it may be triggered either manually, or by radio from a remote control station, or otherwise), the hot gases generated by the explosion cause the twist tube to untwist and the free end of the actuator rotates. The free end of the actuator is connected to the valve stem, and, accordingly, rotational movement of the free end is effective to quickly close (or open) the valve.

Two forms of valve operator are disclosed, each of which embodies the twist-tube actuator. In the one form, the twist-tube actuator is a component part of the manual, or other normal, drive system for opening and closing the valve. In this form, the twist-tube actuator is driven rotationally in both directions, without untwisting, by the normal drive whenever the valve is opened or closed by the normal gear drive.

In the other form of valve operator, the twist-tube actuator is not normally in the drive system. It is coupled to the normal drive system through a novel clutch device. When the cartridge is exploded and the free end of the twist-tube actuator is driven rotationally, the clutch is effective to couple the free end of the twisttube actuator to the valve stem, to drive the valve stem rotationally through the necessary angle to put the valve in the desired position.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is an elevational view, partly in section, illustrating one form of twist-tube actuator, according to the present invention, in which the explosive-cartridge twist-tube actuator is a component part of the normal invention, in which the twist-tube actuator is coupled to the normal drive system through a novel form of clutch.

FIG. 5 is a view, in section, looking down along the line 5-5 of FIG. 4 and showing the worm-drive clutch parts in the positions occupied when the valve is in closed position.

FIG. 6 is a view, in section, looking down along the line 6-6 of FIG. 4 and showing clutch parts in the positions occupied when the twist-tube actuator is unfired and the valve is in closed position.

FIG. 7 is a view, in section, looking along the same line as in FIG. 6 and showing the clutch parts in the positions occupied when the actuator is unfired and the valve is in open position.

FIG. 8 is a view, in section, looking along the same line as in FIG. 6 showing the clutch parts in the positions occupied after the cartridge has been fired and the valve closed by the twist-tube actuator.

FIG. 9 is an exploded perspective view of the component parts of the clutch mechanism which couples the twist-tube actuator to the valve stem.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring to FIGS. 1, 2 and 3, a worm 10 on a worm shaft 17, which may be handwheel or otherwise operated, drives a worm gear 11 supported for rotation in a housing 39. Worm gear 11 is keyed, as by a key 14, to a drive sleeve 12, and the upper end portion of drive sleeve 12 is keyed or splined, as by splines 19, to the lower end portion of a rotatable torque tube 13. The upper end of torque tube 13 is screwed, or bolted, or otherwise secured, to a top plate 18 which is screwed or bolted to the upper end 21 of twist tube actuator 20. The twist-tube actuator 20 includes a helically twisted hollow steel tube 22 which extends from the upper end 21 to a lower base 24. Base 24 is secured as by screws 27 (FIG. 1) to the lower end of the helically twisted tube 22. Base 24 is free to move rotationally relative to torque tube 13 of the valve operator. Base 24 is provided with depending lugs 25, four such lugs being shown. Lugs 25 are received within slots or recesses 26 in the upper end surface of a rotatable sleeve 30. Sleeve 30 is splined or keyed, as by key 32, to the valve stem 35. Valve stem 35 is provided at its lower end with a valve closure element, not shown. The valve closure element may be a butterfly, or plug, or other type such that rotation of the closure element through moves the closure element from fully open to fully closed posi-- explosive charge of known type adapted to be fired.

manually or by remote control, as by radio signal from a remote control station. For an example of a prior art patent disclosing a cartridge-fired twist device, reference may be made to U. S. Pat. No. 3,376,783 to C. R. Olsen, issued Apr. 19, 1968.

In normal operation, the valve stem 35 is moved through the required 90 to open and close the valve closure element by rotating the worm shaft 17, as by a handwheel or otherwise. Worm 10 drives worm gear 11 which is keyed to and drive drive sleeve 12. Sleeve 12 is splined to torquetube l3, and thus torque tube 13 and its plate 18 are driven rotationally. The upper end 21 of twist tube actuator 20 is secured to plate 18 and, accordingly, when torque tube 13 and plate 18 are driven rotationally, the upper end 21 of the helicallytwisted hollow tube 22 is driven rotationally. The twisted tube 22 is made of metal, preferably steel, and is designed to have sufficient strength to retain its twisted form when the upper end 21 is rotated. As a result, the lower base 24 of the twist tube structure is rotated in like manner when the upper end 21 is rotated. When the lower base 24 rotates, the lugs 25 in the slots 26 of sleeve 30 cause sleeve 30 to be also driven rotationally. This rotates valve stem 35 and moves the valve closure element. The device, operating as just described, operates in both directions, to either close or to open the valve, or for that matter, to put the closure element in any position intermediate fully closed and fully open.

Assume now that an emergency condition has arisen and that it is necessary that the valve closure element be moved quickly to its emergency position. The emergency position may be either the fully closed or the fully open position. However, to simplify the description, it may be assumed, during the remainder of this specification, that the emergency position is the fully closed position.

When the emergency arises, the explosive charge of the twist-tube actuator 20, in the upper end 21, is triggered, as by radio signal from a remote control station, or manually by an attendant on the scene. The hot gases generated by the explosion surge through the helically twisted hollow steel tube 22 and cause it to untwist or straighten. As already described, the upper ends of the helical tube 22 is fixed to the upper end 21 of the actuator 20, and end 21 is bolted or otherwise secured to plate 18 or torque tube 13. The lower end of torque tube 13 is now held against rotation by reason of its being keyed or splined to the now motionless drive sleeve 12 which is keyed to worm gear 11 which is locked against rotation by worm which is now motionless. Thus, the upper end 21 of the actuator 20 is held against rotation. Thus, when tube 22 is straightened by the surge of the hot gases therethrough, the lower base 24 of the actuator 20 is driven rotationally in a direction to move the stem 35 rotationally in a direction to move the closure element to the desired closed position.

While the twisted-tube actuator 20 may be designed to effect rotation of its free end 24 through a wide range of rotational movements, in the design of the embodiment of FIGS. 1-3, now being described, it is only necessary that twist device 20 be designed to effect a rotation of 90 of its free end 24 in response to explosion of the charge in its cartridge.

It is to be noted that the twisted tube 22, upon firing, untwists in one direction only, and that the free end 24 is driven in but one direction. Thus, the direction of the helical twist of the tube must be selected to drive the valve stem 35 in the direction desired to move the valve closure element to the desired position, which, in most cases at least, will be the fully closed position.

It is possible that, at the instant of the emergency, the valve closure element will be neither fully opened nor fully closed, but in an intermediate position which requires less than 90 of rotation to put the valve closure element in fully closed, or fully opened, position. In such case, the fact that the twist-tube actuator 20, when filed, attempts to, but cannot, move its free end 24, sleeve 30, and valve stem 35, through a full 90 does no harm to the valve closure element or to the valve operator. The twisted tube 22 of the actuator merely becomes distorted as a result of the inability of the base 24 to move through a full 90.

It is to be noted that, in the form illustrated in FIGS. 1-3, and just described, the twist-tube actuator 20, in its unexploded twisted form, is a component part of the normal drive system. That is to say, the twist-tube device 20 moves rotationally in its twisted form without untwisting, during normal opening and closing of the valve by worm shaft 17 and worm gear 11.

In FIGS. 4-8, there is illustrated a modification in which the twisted-tube actuator 20 is not a part of the normal drive system, but is decoupled therefrom through a clutch arrangement. It is not until the explosive charge of actuator 20 is fired that the twisted-tube actuator 20 becomes coupled, through the clutch, to the valve stem.

Referring now to FIGS. 4-9, the valve operator shown in these figures is similar in a number of respects to that shown in FIGS. 1-3, and corresponding parts are identified by the same reference numerals. The difference between the valve operator of FIGS. I3 and the valve operator of FIGS. 4-9 resides in the fact that in the operator of FIGS. 4-9 the twist-tube actuator 20 is normally decoupled from the worm gear drive system by a clutch mechanism.

As seen in FIG. 4, the drive worm gear 11 is keyed or splined by key or spline 14 to a drive sleeve 52 having a smaller-diameter lower portion and a largerdiameter upper end portion 54 which functions as a clutch drive ring. Referring now to FIGS. 5-9, as well as to FIG. 4, fitted within clutch driven ring 54 is a clutch driven sleeve 60. The clutch driven sleeve has a smaller-diameter lower portion 61 which fits within the smaller-diameter portion of drive sleeve 52, and has a larger-diameter upper portion 62 which fits within and is supported by the clutch drive ring portion 54 of drive sleeve 52. The portion 62 of clutch driven 60 is provided with a through slot 63 having therein a pair of detent rollers 64 and 65. The height of slot 63 is greater than the height of the rollers. The sum of the diameters of rollers 64 and 65 is greater than the thickness of the wall of portion 62, and hence greater than the length of slot 63. Accordingly, a portion of one of the rollers projects beyond one or the other of the ends of slot 63. A recess 55 is provided in the inner wall of clutch drive ring 54 for receiving the projecting portion of roller 64.

Supported within the upper portion 62 of clutch drive sleeve 60 is a cartridge lug ring 40 having projecting upwardly therefrom a lug 41. Lug 41 is semiannular in length, occupying about one-half of the upper surfaces of lug ring 40. Projecting downwardly from the under surface oflug ring 40 is a lug 42 which fits within the upper portion of slot 63, above the rollers 64, 65.

In the form illustrated in FIGS. 4-9, now being described, the upper end 21 of the twist-tube actuator 20 is similar to that of the upper end 21 of twist-tube actuator 20 of FIGS. l-3. In FIGS. 4-9, the upper end 21 is screwed to end plate 18 which is screwed or bolted to the upper end of a torque tube 28 which extends upwardly from and is fixed, as by welding, to the frame or housing 39 of the valve operator. In this respect, the embodiment of FIGS. 4-9 is different from that of FIGS. 11-3. In FIGS. 1-3, the torque tube 13 is rotatable. In FIGS. 4-9, the torque tube 28 is fixed to the frame and is not rotatable.

In FIGS. 4-9, the lower end 24 of the twist-tube actuator has bolted thereto a cap 45 which is coupled, as by key or spline 46, to a cartridge drive lug member 50. Member 50, as best seen in FIG. 9, has a largerdiameter upper portion 55, a reduced-diameter intermediate portion 56 and a still smaller-diameter lower portion 57. Projecting downwardly from the annular undersurface of upper portion 55 is a lug 58, a face of which is adapted to abut against a face of upstanding lug 41 of lug ring 40. The outer surface of the intermediate portion 56 is provided with a recess 59 for receiving a portion of roller 65, as will be described. The smaller-diameter lower portion 57 is received within the bore of drive sleeve 61.

In normal operation of the embodiment of FIGS. 4-9, worm gear 11, through key or splines 14, drives drive sleeve 52 the upper enlarged-diameter end of which forms the clutch drive ring 54. If the valve is in the closed position, the slot 63 is in the position illustrated in FIGS. 5 and 6. If the valve is in the open position, the slot 63 is in the position shown in FIG. 7. In either case, with the charge of cartridge device 20 unexploded, the

cartridge twist-tube actuator 20, its base 24 and cap 45,

and the cartridge drive lug member 50 are in the fixed angular positions illustrated in FIGS. 6 and 7, and also in FIGS. 4 and 9.

In the unfired condition of the cartridge device 20, the recess 59 in the intermediate portion 56 of the cartridge drive lug member 50 faces the solid wall or land portion of the upper portion 62 of clutch drive sleeve 60, but slot 63 of said portion 62 of clutch drive sleeve 60 is in registry with recess 55 of clutch drive ring 54. Thus, when drive sleeve 52 is driven rotationally by worm gear 11, the clutch drive ring 54 drives clutch drive sleeve 60 rotationally through the detent rollers 64, 65. The direction of the angular movement depends, of course, upon the direction of rotation of the drive worm. Since clutch drive sleeve 60 is connected by key 32 to the valve stem 35, the valve stem is driven. Clutch drive sleeve 60 and valve stem 35 are driven 90 in one direction to close the valve, and 90 in the opposite direction to open the valve. FIGS. 4, 5 and 6 illustrate the position of the component parts when the valve is in closed position and the cartridge is unfired. F I68. 7 and 9 illustrate the positions of the parts when the valve is in open position and the cartridge is unfired. FIG. 8 illustrates the position of parts after firing.

In an emergency situation, when the explosive charge in the cartridge of the twisted-tube actuator 20 is fired, the upper end 21 is held fixed against rotation by plate l8 and torque tube 28 but the lower end 24-and cap 45 are driven clockwise when the tube 22 untwists. Cap 45 is splined to cartridge drive lug member 50 and member 50 is driven rotationally. It is assumed, in the drawings and in the present description, that when the emergency condition occurs, the valve is in the fully open position and that it is important that the valve be closed as quickly as possible. FIG. 7 illustrates the angular position of lug 58 relative to that of the semi-annular lug 41 of lug ring 40 when the valve is fully open. This condition is also illustrated in FIG. 9. It will be understood that the angular position of clutch drive sleeve 60 which, in response to worm drive, is in turn controlled by the clutch drive ring 54.

tion indicated in these same figures. As the twisted tube 22 untwists, cap 45 and cartridge drive lug member 50 are driven rotationally, clockwise as viewed in FIGS. 7 and 9, and depending lug 58 moves toward the upstanding lug 41 of lug ring 40. The face 158 of lug 58 meets face 141 of lug 41 and as lug 58 continues its clockwise movement, lug 41 is driven rotationally, clockwise as viewed in FIGS. 7, 8 and 9. This clockwise rotation of lug 41 and lug ring 40 drives clutch driven sleeve 60 clockwise, due to the fact that dependent lug 42 of ring 40 projects into the upper part of slot 63.

It is to be noted that when face 158 of lug 58 meets face 141 of lug 41, the recess 59 of the intermediate portion 56 of the cartridge drive lug member 50 arrives opposite and in registry with slot 63 of the-clutch drive sleeve 60. Thus, as lug 58 continues its clockwise movement, driving lug ring 40 along with it, the detent roller 64 is cammed out of recess in the clutch drive ring 54 and the other roller 65 is forced into recess 59. In this manner, the clutch drive sleeve is decoupled from the clutch drive ring 54. As lug 58 and lug 41 continue to move clockwise the lug ring 40 continues to drive the clutch drive sleeve 60 clockwise through the lug 42 in slot 63 and detent rollers 64 and 65 with a portion of roller 65 being maintained in recess 59 of the cartridge drive lug member 50. This clockwise movement of the clutch drive sleeve 60 drives valve stem 35 through key 32. This continues until the twist tube 22 has been fully straightened. The extent to which the free end 24 of the twist-tube actuator 20 rotates before the tube 22 is fully straightened is a matter of design. In the present illustration, the design would call for a rotation in excess of to allow the lug 58 to move from the rest or unfired position shown in FIG. 7 to meet the face 141 of lug 41, after which the face 141 v of lug 41 is moved through 90 from the position shown in FIG. 7 to the position shown in FIG. 8. If desired, a stop element may be provided to stop rotation of the valve stem 35 after it has been driven to the fully closed position.

In FIG. 4, a site window 67 is illustrated at the right hand side of the structure. Suitable markings such as OPEN and CLOSED, and also suitable intermediate markings therebetween may be placed on an arcuate indicated scale 69 mounted on the lug ring 40 and mo vable therewith so that information as to the position of the valve is visible through the window.

While the invention has been described as applied to a rotary actuator, the invention has a broader scope of application and may be employed in other suitable apparatus and environments where a load shaft is to be 6 When the explosive charge is fired, the lug 58 IS, as

just described, in the angular position illustrated in FIGS. 6, 7 and 9, and recess 59 is in the angular positurned.

What is claimed is: l. A valve operator comprising: a. a housing; b. a valve stem; c. gear drive means; (1. an explosive twist-tube actuator;

e. means coupling said gear drive means to said valve stem to drive said stem rationally;

f. means effective upon firing of said explosive twisttube actuator for driving said valve stem rotationally while said gear drive means is stationary.

2. A valve operator according to claim 1 characterized in that said means coupling said gear drive means to said valve stem includes said explosive twist-tube actuator in unfired twisted condition.

3. A valve operator according to claim 1 characterized in that said means coupling said gear drive means to said valve stem includes:

a. a worm;

b. a worm gear coupled to and driven by said worm;

c. a drive sleeve connected to and driven by said worm gear;

d. means connecting said drive sleeve to one end of said twist-tube actuator;

e. means coupling the other end of said twist-tube actuator to said valve stem.

4. A valve operator according to claim 3 characterized in that said means coupling the other end of said twist-tube actuator to said valve stem includes a second sleeve connected to said valve stem.

5. A valve operator according to claim 1 characterized in that:

a. said means coupling said gear driven means to said valve stem is exclusive of said explosive twist-tube actuator;

b. one end of said twist-tube actuator is fixed to said housing, the other end being free to rotate.

6. A valve operator according to claim 5 characterized in that clutch means are provided for decoupling said explosive twist-tube actuator from said valve stem when in unfired condition, and for coupling said free end of said twist-tube actuator to said valve stem and simultaneously uncoupling said gear drive means in response to the firing of said explosive twist-tube actuator.

7. A valve operator according to claim 6 further characterized in that:

a. said clutch means is effective to maintain said free end of said twist-tube actuator decoupled from said valve stem when said explosive twist-tube actuator is in unfired condition;

b. said clutch means is effective to couple said free end of said twist-tube actuator to said valve stem in response to firing of said explosive twist-tube actuator;

c. said clutch means is effective upon firing of said twist-tube actuator to uncouple said worm-gear drive sleeve.

8. A valve operator according to claim 7 characterized in that:

a. a second drive sleeve is provided;

b. means are provided coupling said second drive sleeve to said valve stem;

c. said clutch means includes means for coupling said worm-gear drive sleeve to said second drive sleeve when said twist-tube actuator is in unfired condition;

d. said clutch means, in response to firing of said twist-tube actuator, is effective to uncouple said second drive sleeve from said worm-gear drive sleeve and to couple said twist-tube actuator to said second drive sleeve.

9. A valve operator according to claim 8 characterized in that said clutch means includes detent rollers which in one position couple said worm-gear drive sleeve to said second drive sleeve and in another position couple said explosive twist-tube actuator to said second drive sleeve.

10. In a rotary drive having a housing, a load shaft and gear drive means for normally driving said load shaft, the improvement which includes the incorporation of an auxiliary drive for effecting rapid rotation of the load shaft through a limited angular movement to a desired emergency position, said auxiliary drive means comprising:

a. an explosive actuator comprising an elongated twisted tube connected to a base at each end, said twisted tube being adapted to untwist and to move one of said bases rotationally in response to firing of said explosive;

b. means connecting said one ofsaid bases to the load shaft;

0. means connecting the other of said bases to the normal gear drive means.

11. In a rotary drive according to claim 10 characterized in that said means connecting said one base of said explosive actuator to said load shaft includes:

a. a clutch mechanism;

b. said gear drive means is normally coupled to said load shaft through said clutch mechanism;

c. said actuator in unfired condition is decoupled from said load shaft.

12. In a rotary drive according to claim 11 characterized in that said clutch mechanism includes:

a. means effective after firing of the explosive of said actuator for decoupling said normal gear drive means from said load shaft and for coupling said actuator to said load shaft.

- UNITED STATES PAJIEN'I OFFICE I @ERTIFICATE or CORRECTION f patent 3,766,803 Da ed October 23, 1973 Inventor(s) ell C. Ball, Jr, and Walter J. Denkoweki It is certified that errorapp'ears in the aboveidentified petent and that said Letters Patent are hereby corrected as shown below:

Column 6, line 61, Claim "1, Clause (e) the last word should read -rotationally--.rather than "rationally".

Signed and sealed this 24th day of September 1974.

(SEAL) Attes t:

McCOY M. GIBSON JRv Attesting Officer 0.. MARSHALL DANN Commissioner of Patents Patent No. ,766 ,803

UNITED STATES PATENT- OFFICE. v CERTIFICATE OF CORRECTION" Dated October 23, 1973 lnventofl Russell C. Ball, Jr.; and Walter J. Denkowski It is certified that error appears in the above-identified petent and that said Letters Patent arehereby corrected as shown below:

Column 6, line 61, Claim' l Clause (e) the last word should read --rotationally-vrather than "rationally".

Signed and sealed this 24th day of September 1974.

(SEAL) Attest:

McCOY M. GIBSON JR Attesting Officer 0. MARSHALL DANN Commissioner of Patents 

1. A valve operator comprising: a. a housing; b. a valve stem; c. gear drive means; d. an explosive twist-tube actuator; e. means coupling said gear drive means to said valve stem to drive said stem rationally; f. means effective upon firing of said explosive twist-tube actuator for driving said valve stem rotationally while said gear drive means is stationary.
 2. A valve operator according to claim 1 characterized in that said means coupling said gear drive means to said valve stem includes said explosive twist-tube actuator in unfired twisted condition.
 3. A valve operator according to claim 1 characterized in that said means coupling said gear drive means to said valve stem includes: a. a worm; b. a worm gear coupled to and driven by said worm; c. a drive sleeve connected to and driven by said worm gear; d. means connecting said drive sleeve to one end of said twist-tube actuator; e. means coupling the other end of said twist-tube actuator to said valve stem.
 4. A valve operator according to claim 3 characterized in that said means coupling the other end of said twist-tube actuator to said valve stem includes a second sleeve connected to said valve stem.
 5. A valve operator according to claim 1 characterized in that: a. said means coupling said gear driven means to said valve stem is exclusive of said explosive twist-tube actuator; b. one end of said twist-tube actuator is fixed to said housing, the other end being free to rotate.
 6. A valve operator according to claim 5 characterized in that clutch means are provided for decoupling said explosive twist-tube actuator from said valve stem when in unfired condition, and for coupling said free end of said twist-tube actuator to said valve stem and simultaneously uncoupling said gear drive means in response to the firing of said explosive twist-tube actuator.
 7. A valve operator according to claim 6 further characterized in that: a. said clutch means is effective to maintain said free end of said twist-tube actuator decoupled from said valve stem when said explosive twist-tube actuator is in unfired condition; b. said clutch means is effective to couple said free end of said twist-tube actuator to said valve stem in response to firing of said explosive twist-tube actuator; c. said clutch means is effective upon firing of said twist-tube actuator to uncoUple said worm-gear drive sleeve.
 8. A valve operator according to claim 7 characterized in that: a. a second drive sleeve is provided; b. means are provided coupling said second drive sleeve to said valve stem; c. said clutch means includes means for coupling said worm-gear drive sleeve to said second drive sleeve when said twist-tube actuator is in unfired condition; d. said clutch means, in response to firing of said twist-tube actuator, is effective to uncouple said second drive sleeve from said worm-gear drive sleeve and to couple said twist-tube actuator to said second drive sleeve.
 9. A valve operator according to claim 8 characterized in that said clutch means includes detent rollers which in one position couple said worm-gear drive sleeve to said second drive sleeve and in another position couple said explosive twist-tube actuator to said second drive sleeve.
 10. In a rotary drive having a housing, a load shaft and gear drive means for normally driving said load shaft, the improvement which includes the incorporation of an auxiliary drive for effecting rapid rotation of the load shaft through a limited angular movement to a desired emergency position, said auxiliary drive means comprising: a. an explosive actuator comprising an elongated twisted tube connected to a base at each end, said twisted tube being adapted to untwist and to move one of said bases rotationally in response to firing of said explosive; b. means connecting said one of said bases to the load shaft; c. means connecting the other of said bases to the normal gear drive means.
 11. In a rotary drive according to claim 10 characterized in that said means connecting said one base of said explosive actuator to said load shaft includes: a. a clutch mechanism; b. said gear drive means is normally coupled to said load shaft through said clutch mechanism; c. said actuator in unfired condition is decoupled from said load shaft.
 12. In a rotary drive according to claim 11 characterized in that said clutch mechanism includes: a. means effective after firing of the explosive of said actuator for decoupling said normal gear drive means from said load shaft and for coupling said actuator to said load shaft. 